Process for preparing hexamethylenediamine compounds from 5-aminomethyl-2-furfurylamine compounds



United States Patent PROCESS FOR PREPARING HEXAMETHYLENEDI- AMINE COMPOUNDS FROM S-AMINOMETHYL- Z-FURFURYLAMINE COMYOUNDS John D. Garber, Westfield, and Robert A. Gasser, North Plainfield, N .J., and Robert Ellery Jones, North Mnskegon, Mich., assignors to Merck 8: Co., Inc, Rahway, N.J., a corporation of New Jersey No Drawing. Filed Jan. 16, 1962, Ser. No. 166,697

8 Claims. (Cl. 260-583) This invention relates to the preparation of aliphatic amino compounds. More particularly it relates to a method for obtaining aliphatic amino compounds from fur-an compounds. Specifically, it relates to the preparation of hexamethylene-diamine from -aminomethyl-2- furfurylamine, its alkylated and alkanoylated derivatives and its acid addition salts.

This application is a continuation-in-part of copendin'g application Serial No. 760,057 filed September 10, 1958, now abandoned.

Hexame-thylenediamine is an important intermediate in the preparationof synthetic fibrous materials, such as, for example, nylon. It would be extremely desirable to provide the industry with a simple process for obtaining this compound from relatively inexpensive and readily accessible starting materials. Such starting materials are represented by S-aminomethyl-Z-furfurylamine, its lower alkylated and alkanoylated derivatives and its acid addition salts. From the vast amount of knowledge compiled with regard to the chemistry of furan compounds,

it is generally known that when such compounds are subjected to hydrogenation, a wide variety of reaction products are obtained. However, previous attempts at ob taining any one compound in good yield from furan compounds have been futile, in consequence ofv the many side reactions taking place. It is an object of this invention to provide a process for hydrogenating a particular group of furan compounds to obtain good yields of an aliphatic diamine. It is a further object of this invention to provide a process for producing hexamethylene-diamine from 5-aminomethyl-Z-furfurylamine audits derivatives to the substantial exclusion of ring saturated furans and hydroxy substituted hexamethylenediamine.

In accordance with the present invention it has been discovered that hexamethylenediamine may be produced in good yield from 5-aminomethyl-2-furfurylamine, its lower alkylated or alkanoylated derivatives and its acid addition salts, by hydrogenating the starting material in the presence of a large amount of platinum catalyst, a lower aliphatic acid and a mineral acid. When carried out using the critical reaction conditions hereinafter specified, the process is essentially devoid of the detrimental side reactions normally considered to accompany the hydrogenation of furan compounds, and there are obtained yields of 'hexamethylenediamine ranging from about 25% to 60% and higher. The following flow diagram represents the conversion of the star-ting materials;

where R R R and K; may be hydrogen, lower alkyl or lower alkanoyl. Typical of the compounds which 3,189,651 Patented June 15, 1965 methyl-Z-furfurylamine, N,N'-diacetyl 5-aminomethyl-2- furfurylamine, N,N-dipropionyl S-aminomethyl-Z-furfurylamine, N-butyl S-aminomet-hyl-Z-furfurylamine and the like, and the acid addition salts of these compounds as exemplified by those obtained when these compounds are treated with such acids as acetic acid, propionic acid, butyric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, and the like.

The success of the method of the present invention is contingent upon using relatively large amounts of the catalyst in carrying out the hydrogenation in combination with a lower aliphatic acid and a mineral acid. The catalyst employed is platinum oxide as charged to the reaction system. Under the reaction conditions employed, however, the oxide is converted to elemental platinum, and it is the free metal which acts as the catalyst. In particular, the amount of catalyst used, for either a batch process or a fixed bed reactor must be equivalent to at least 0.25 mole of platinum per mole of starting material being hydrogenated. The preferred range however, is between 0.5-2.0 moles of catalyst per mole of starting material although larger amounts may be used if desired. When the reaction is run over a fixed catalyst bed, it is preferred to have as high a ratio as possible. It will be appreciated by those-skilled in the art that the ratio values may be converted to units more commonly used in that sphere of technology by considering the volume of fixed catalyst, volume flow rate of the reaction mixture thereover and the like.

The mineral acids used in the process of the present invention are exemplified by hydrochloric, hydrobromic,

' hydrofluoric, sulfuric and phosphoric acid and various forms of phosphoric acid, such as metaphosphoric, polyphosphoric and phosphorous acids. The lower aliphatic acid may be supplied as the free acid or by way of any acid soluble salt thereof such as the alkaline earth and alkali metal salts, which upon contact with the mineral acid will be converted to the free organic acid. Typical of the aliphatic acids which may be employed are acetic acid, propionic acid, butyric acid and the like. 'With re gard to the amounts of each of these to be used, it has been found that the mineral acid should be supplied in a ratio of at least 0.5 mole per mole of the starting material. The preferred range for optinum results is between 1 and 5 moles of acid per mole of starting material. The amount of the aliphatic acid supplied is not critical. It is preferred, however that it be present in large excess, since one of its functions is to serve as a solvent. The preferred range is between 10 and 100 moles per mole of starting material although values outside this range will yield suitable results. i

It is one of the advantages of the present invention, that hexamethylenediamine, its derivatives and acid'addition salt-s, may be obtained from the furan starting materials by using very mild hydrogenation conditions. For example, the reaction requires temperatures no higher than 150 C. The preferred operating range however, is between 15 C. and CL Lower temperatures may be employed though without any beneficial result. The hydrogen pressure employed is similarly mild. Pressures slightly greater than atmospheric and preferably ranging from Z0 to lbs. per square inch gauge yield suitable results, although pressures as high as 10,000 lbs. per square inch may be employed without detrimentally affecting the yield of the process.

In a preferred embodiment of the instant process, it

is desirable to preheat a mixture of the starting material and the acids, with or without the catalyst. A preheating temperature of between about 30 and 100 C. for a period of from 5 to 60 minutes will generally be suitable. Where the subsequent hydrogenation takes acetate and the like.

"tration only and are not intended furic acid, similar results are obtained.

7 placenta temperature about 30 C. and above, the 'preheating'is accomplishedlduring the hydrogenation.

Where however the hydrogenation is run at temperatures below about 30 C:, it is desirableto include the. preheating step at the above indicated temperatures. It

will be understood however'thatgthe term preheat as used herein is meant to be inclusive of allowing the reaction mixture to stand for extended periods of time at room temperature and below prior to hydrogenation.

' V At the conclusion of the reaction, the final product exists'in solution as the acid: addition salt of the start- 7 7 ing amine corresponding to the particular acids used in the reaction, or as the tree alkylated or alkanoylated compound if there are no basic hydrogen atoms present on the original starting material.' The desired product,

hex'amethylenediarnine, maybe isolated from the re-action mixture by techniques well'known in the art. For

example, the reaction mass maybe filtcred'f-rce of the catalyst and the clear fil-trate neutralized with'base such as, for example sodium, potassium or calcium hydroxide,

' calcium oxide, sodium carbonate, and the like; so as to a convert the salt to the free amine. ,7 Where the-final prod- 7 uct1is in the tormof the al-kylated or alkanoylated compound, the filtrate maybe treated with base and refluxed to re'rriovethe alkyl or alkanoyl radical by saponiiica- Example 111 The procedure of Example I is followed except that, prior to the addition of theplatinum oxidethe starting. material is preheated at 50 for 1-0 minutesand then. hydrogenated at 25 for 3 hours under"4.0 lbs. per square 7 inch gauge of hydrogenpressurefThe product hexa- V 'rnethylenediamine is obtained in 52% yield: 1

, procedure, the yield of final product is-of the .orderof tion. This isjparticularly desirable When the hydrogena- 1 tion has been carried out at the higher temperatures here-- in indicated; for the reason that during the reaction the final product may have been alkanoylate'd by the ali- I phatic acids employed. The free amine may'thereafter.

be obtained by sublimation or distillation in vacuum or V by. solvent extraction using inert,- polar, water-immiscible solvents such as for-example; methylene chloride, ethyl The, S aminomethyli furfurylamine used in the process of the present invention may be prepared in accord- I ance'with the method disclosed in US. Batent 2,989,546. The alkylated and alkanoylated com-pounds and the acid addition saltsfof these com-pounds may be prepared from the free amine'by'means well known in the art.

The following'examples are given for purposes of illusto limit the scope of e r sent invention; 7

. Example] 3.0 g, 0.03 mol) of 98% sulfuric acid. Crystals of the sulfate salt format once; The mixture is heated. to 6 065 C. and held at that temperature for 10 minutes.

' Then 4.0 g. of Pro, (0.0175 rhol) is added and the mix ture shaken at apressure of 40 p.s.i.g. of hydrogen at- V 50 C. 7 After the reaction'is'com-plete the catalyst is removed byfiltration and the water-Whitefiltrate stirred with 5.4 g. (0.065 mol) of sodium acetate to neutralize the sulfuric acid.;The acetic acid is removed as completely as possible via vacuum distillation. The residue is dissolved in ater and .made basic with caustic, refluxed for a short time to insure the hydrolysis of any .acetylatedhexamethylenediamine and extractedwith methylene chloride. The solvent layer is dried and the To 1.26'g. (-0.01mole) for 5-aminomethyl-Z-fnrfuryl amine dissolved-inSO m1. of glacial acetic acid is added i 20% yield of 2-hydroxy product hexamethylenediamine .isrecovered by sublima .tion at between 70120' C. at 0.40 mm. in 44% yield;

' Only minor amounts of 2-hydroxy 1,6 hexanediamine and 5-aminomethyl 2 tetrahydrofurfurylamine .are formed. 7

When the above procedure is repeated using equivalent amounts of hydrochloric acid, hydrobr-omic acid, hydrophosphoric acid, or phosphorous acid in place of the-sul- Example II V a r The procedure of Example I is repeated except that a 7 hydrogen pressure of 6,000 p.s.i.'is employed. 'T here are no significant changes in yield.

, fiuoric acid, phosphoric acid, mctaphosphoric acid, poly 7 When hydrogenation conditions of 140 C. and 20 p.s.i.g. are employed in the above PI'OCliH-l'fi; there is no significant change in yield. a

When the preheating step is eliminated from theabove Similar results are obtained or butyric acidin place of theacetic acid.

Example IV. 0

The procedure: of Example is'followed except that prior to the addition 'ofthe-platini1rn catalyst thelreac- 1. tionmixture' is. preheated for 30 minutes at 50 CQ and then hydrogenated for 6hour's at 100 C. under hydrogen.

pressure of .40 lbs. per square inch.. Thehexamethylenediamine is obtained in 34% yield.

. When this procedure is-repeated using half the amount nd hydrogenated at C. for o /z hours;

of the catalyst a the yield of final product is 42%1 amine. h

7 Example 1 This experiment shows theeilect of thetab'sence of a mineral acid on the yield of hexamethylenediamine. I

' 'To a solution of.1.25 0.01 mol) of S-arninomethyh 'Z-turfurylamine in 50 mlr-gl-aci'al acetic acid is added 0.5 a

g. of platinum 'oxidecatalyst. The mixture is subjected to hydrogenationiconditions of? 1000 .p.s.i.g."ait 1 50 C. for'20 hours. AfterWdrk-up as inExamplejLthere re sultsya 33% yield of 2 -hydroxy l,6hexaned iamine'and only minor amounts ofhexamethylenediamine. 7 v j Example 1 1 This experiment showsthe eifectotthe absence of the acetate ionon the yield of hexamethylenediamine,

To a solutionof 1.26 g. of 5-aminomethyl-2 furfuryl amine in 65 m1. oi Water containing 0.043 moleofhydrochlo'ric acid is added' 0.5 g. of platinum oxide. Hydroe genation is commenced at 40 p.s.i.g.iand 25 C. and terg 'minated when hydrogen up -take'ceases. The. filtrateis I treated in-the manner of Example -I and there results a 1,6-hexanediamin'e and 'onlyasmall 7 amount of hexamethylenediarnine.

. It will be obvious to those skilled in the-artjthat c er- -tain changes and modifications maybe madein the process of the present invention Without departing frornthe' spirit andscope thereof. All such changesand modifications are intended to be encompassed within theappended claims. a '0 7 What is claimed is':

1. The process for. preparing acid addition compounds having the structural formula J Bi Y Nonzonzonzonzomonzn R2 I 7 R4 wherein R R R and R are selected from the group? consisting of hydrogen, lower alkyl and lower alkanoyl 7 when the above procedure is repeated using an equivalent amount of pr-opionic acid salts of which comprises treatifiga'furan compound of the formula with hydrogen in the presence of a platinum catalyst, a lower aliphatic acid having less than 5 carbon atoms and a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, metaphosphoric acid, polyphosphoric acid and phosphorous acid at a temperature less than 150 C. and a pressure greater than atmospheric pressure and wherein said catalyst is present to the extent of at least 0.25 mole per mole of said furan compound.

2. The process for preparing acid addition salts of hexamethylenediamine which comprises treating S-aminomethyl-Z-furfurylamine with hydrogen in the presence of a platinum catalyst, acetic acid and a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, metaphosphoric acid, polyphosphoric acid and phosphorous acid at a temperature less than 150 C. and a pressure greater than atmospheric pressure and wherein said catalyst is present to the extent of at least 0.25 mole per mole of said S-aminomethyl-Z-furfurylamine.

3. The process for preparing acid addition salts of hexamethylenediamine which comprises contacting S-aminomethyl-Z-furfurylamine with hydrogen in the presence of a platinum catalyst, acetic acid and sulfuric acid at a temperature less than 150 C. and a pressure greater than atmospheric and wherein said catalyst is present to the extent of at least 0.25 mole per mole of said S-aminomethyI-Z-furfurylamine.

4. The process for preparing acid addition salts of hexamethylenediamine which comprises contacting 5-aminomethyl-Z-furfurylamine with hydrogen in the presence of a platinum catalyst, acetic acid and sulfuric acid at a temperature between 15 C. and 75 C. and at a pressure between 20 and 100 lbs. per square inch gauge and wherein said catalyst is present to the extent of between 0.5-2.0 moles per mole of said S-aminomethyl-Z-furfurylamine, said acetic acid is present to the extent of between -100 moles per mole of said S-aminomethyl-Z-furfurylamine and said sulfuric acid is present to the extent of between 0.5-5 moles per mole of said S-aminomethyl-Z-furfurylamine.

5. The method for preparing hexamethylenediamine which comprises contacting 5-aminomethyl-2-furfury1- amine with hydrogen in the presence of a platinum catalyst, a lower aliphatic acid having less than 5 carbon atoms and a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, metaphosphoric acid, polyphosphoric acid and phosphorous acid at a temperature less thaii 150 C. and a pressure greater than atmospheric pressure and wherein said catalyst is present to the extent of at least 0.25 mole per'mole of said 5- 6. The method for preparing hexamethylenedihiiheii which comprises contacting S-aminomethyl-Z-furfuryl- I amine with hydrogen in the presence of a platinum catalyst, acetic acid and sulfuric acid at a temperature of between 15-75 C. and a pressure of between -100 lbs. per square inch gauge and wherein the platinum catalyst is present to the extent of between 0.5-2.0 moles per mole of 5aminomethyl-2-furfurylamine, .the acetic acid is present to the extent of between 10-100 moles per mole of 5- aminomethyl-Z-furfurylamine and the sulfuric acid is present to the extent of between 1-5 moles per mole of 5-aminomethyl-Z-furfurylamine and thereafter neutralizing the product thus obtained with base.

7. The method for producing acid addition salts of hexamethylenediamine which comprises heating a mixture comprising S-aminomethyl-Z-furfurylamine, a lower aliphatic acid having less than 5 carbon atoms and a mineral acid selected from the group consisting of sulfuric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, phosphoric acid, metaphosphoric acid, polyphosphoric acid and phosphorous acid at a temperature of greater than approximately C. and thereafter treating said mixture with hydrogen in the presence of a platinum catalyst at a temperature less than C. and a pressure greater than atmospheric pressure and wherein said catalyst is present to the extent of at least 0.25 mole per mole of 5-aminomethyl-Z-furfurylamine.

8. The method for producing acid addition salts of hexamethylenediamine which comprises heating a mixture comprising S-aminomethyl-Z-furfurylamine, acetic acid and sulfuric acid at a temperature of greater than approximately 30 C. and thereafter treating said mixture with hydrogen in the presence of a platinum catalyst at a temperature between 1575 C. and a pressure between 20-100 lbs. per square inch gauge and wherein said catalyst is present to the extent of between 0.5-2.0 moles per mole of 5-aminomethyl-2-furfurylamine, said acetic acid is present to the extent of 10-100 moles per mole of 5- aminomethyl-Z-furfurylamine and said sulfuric acid is present to the extent of between 1-5 moles per mole of S-aminomethyl-Z-furfurylamine.

References Cited by the Examiner Kaufmann et al.: I. Am. Chem. Soc., volume 45, pages 3029-44 (1923).

Keimatsu et al.: Chem. Abstract, volume 21, page 3362 1927).

Bailey et al.: I. Am. Chem. 500., volume 71, pages 2886-2889 (1949).

CHARLES B. PARKER, Primary Examiner.

Patent No. 3,189,651 June 15, 1965 John D Gerber et 9.10

It is hereby certified that err ent requiring correction and that th corrected below.

or appears in the above numbered pate said Letters Patent should read as Colomn 2, line 3, for "N-butyl" read N-butryl column 4, line 4, for "50" read 50 C. line 5, for

"25" read 25 C. same column 4, line 41, for "1,25" read 1,26 --c Signed and sealed this 7th day of December 1965.

(SEAL) Altest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. THE PROCESS FOR PREPARING ACID ADDITION SALTS OF COMPOUNDS HAVING THE STRUCTURAL FORMULA 